aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/python/ipython/py3/IPython/utils/syspathcontext.py
blob: bd1c51500d60a127eb197a97df1b7449c485e33b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
# encoding: utf-8
"""
Context managers for adding things to sys.path temporarily.

Authors:

* Brian Granger
"""

#-----------------------------------------------------------------------------
#  Copyright (C) 2008-2011  The IPython Development Team
#
#  Distributed under the terms of the BSD License.  The full license is in
#  the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------

import sys


class appended_to_syspath(object):
    """A context for appending a directory to sys.path for a second."""

    def __init__(self, dir):
        self.dir = dir

    def __enter__(self):
        if self.dir not in sys.path:
            sys.path.append(self.dir)
            self.added = True
        else:
            self.added = False

    def __exit__(self, type, value, traceback):
        if self.added:
            try:
                sys.path.remove(self.dir)
            except ValueError:
                pass
        # Returning False causes any exceptions to be re-raised.
        return False

class prepended_to_syspath(object):
    """A context for prepending a directory to sys.path for a second."""

    def __init__(self, dir):
        self.dir = dir

    def __enter__(self):
        if self.dir not in sys.path:
            sys.path.insert(0,self.dir)
            self.added = True
        else:
            self.added = False

    def __exit__(self, type, value, traceback):
        if self.added:
            try:
                sys.path.remove(self.dir)
            except ValueError:
                pass
        # Returning False causes any exceptions to be re-raised.
        return False